Any advice as far as lowering hydrocarbons and Carbon monoxide?? My 1995 failed bigtime today and I have been cleaning my EGR and replacing my PCV. The O2 sensors will be next if I fail again in the morning then onto replacing the cat.
Anybody else had this problem and how did you resolve it?
Thanks

 

I would suspect the cat would be the main culprit. When my old truck failed a test, I had to replace the cat to get the CO and NOx down to levels.

 

I would think that the O2 sensor could be the CO problem and the Cat could be the NOx....but...there are many possibilities.
If the coolant sensor is reading to cold then there is a request to richen the fuel supply, if you have a bad plug or wire or contaminated engine oil your NOx will be to high...in other words, it's hard to guess and be accurate.
Do you have any small vacuum leaks????

 

After doing the plugs, pcv, egr and oxygen sensors I still failed miserably. Looks like another $120 to get a cat put on. Hopefully that will take care of it. No vacuum leaks.

 

Passed today after changing out the plugs, plug wires, egr, O2 sensors and the cat. It cost me $300 to make Al Gore happy. No biggie since the truck now runs like ti did 10 years ago.

 

If you want to make Al Gore happy, you have to junk your blazer, ride a bike and use one square of toilet paper the rest of your life.

Or you could just buy a Toyota Prius, even though they do more harm to the environment than driving a Hummer.

 

aint that the truth al gore can go @#[email protected]@$ and some lol sorry ex military didn't care for al gore or the bush administration